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The calory percentages of the ingredients in th:final regimen, i.e., basal diet plus ethanol solution, consumed by the animals of the alcohol group were as follows:-ethanol, 41.5%; carbohydrate> 42.6%; lipid, 6.6% and protein, 9.3%. The composition of the diet of the control group was the same except that the ethanol-derived calories were replaced by sucrose.The animals in the ethanol group \lere kept witbhout ethanol for 18 h prior to the experiment but were allowed access to the basal diet and to drinking water. Male

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Mice lacking the 66 kDa isoform of the adapter molecule shcA (p66 shcA ) display increased resistance to oxidative stress and delayed aging. In cultured cell lines, p66 promotes formation of Reactive Oxygen Species (ROS) in mitochondria, and apoptotic cell death in response to a variety of pro-oxidant noxious stimuli. As mitochondrial ROS and oxidative cell damage are clearly involved in alcohol-induced pathology, we hypothesized that p66 may also have a role in ethanol. In vivo, changes observed in p66 þ / þ mice after 6-week exposure to ethanol in the drinking water, including elevated serum alanine aminotransferase (ALT), liver swelling and evident liver steatosis, were significantly attenuated in p66À/À mutant mice. Biochemical analysis of liver tissues revealed induction of the p66 protein by ethanol, whereas p66-deficient livers responded to alcohol with a significant upregulation of the mitochondrial antioxidant enzyme MnSOD, nearly absent in control mice. Evidence of an inverse correlation between expression level of p66 and protection from alcohol-induced oxidative stress was also confirmed in vitro in primary hepatocytes and in HepG2-E47 cells, an ethanol-responsive hepatoma cell line. In fact, MnSOD upregulation by exposure to ethanol in vitro was much more pronounced in p66KO versus wild-type isolated liver cells, and blunted in HepG2 cells overexpressing p66shc. p66 overexpression also prevented the activation of a luciferase reporter gene controlled by the SOD2 promoter, indicating that p66 repression of MnSOD operates at a transcriptional level. Finally, p66 generated ROS in HepG2 cells and potentiated oxidative stress and mitochondrial depolarization by ethanol. Taken together, the above observations clearly indicate a role for p66 in alcohol-induced cell damage, likely via a cell-autonomous mechanism involving reduced expression of antioxidant defenses and mitochondrial dysfunction.

Mitochondrial mass was determined in the heart and liver of rats submitted to 4,400 m (simulated altitude) for 9 mo and their controls at sea level. This was done 1) by evaluation of isolated mitochondrial protein per gram of tissue, 2) by evaluation of the ratio between cytochrome oxidase activity in tissue homogenate and in isolated mitochondria, and 3) by evaluation of mitochondrial numerical and volume density in fixed tissues analyzed by electron microscopy. An increase in mitochondrial mass and a more homogeneous distribution of mitochondria were found in liver. In cardiac tissue an increase in numerical density of mitochondria accompanied by a slight decrease in their mean volume was observed. Maximal physiological rate of mitochondrial respiration (state 3, active respiration), resting respiration, ADP/O, and acceptor control ratio were determined in the isolated mitochondria. No differences were found in the intrinsic properties of mitochondria. The results suggest that chronic mild hypoxia promotes tissue adaptation by increasing the mitochondrial mass or number in liver and heart, respectively, and improves intracellular O2 diffusion by adopting a more homogeneous intracellular distribution of mitochondria in the liver.

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